The relationship between humans and animals is a quickly growing field of academic and research study that is of interest to veterinarians along with human health-care providers and researchers and psychologists. Studies have clearly disclosed that humans in relationship with animals experience beneficial physiological affects like stabilization of blood pressure and heart rate, reduction of anxious feelings and increase of feelings of well being. It has been shown that these sorts of benefits are not restricted to humans as the animals in these relationships gain physiological benefits at the same time that they confer them. Ethics enter into the relationship between animals and humans because (1) humane and compassionate care of pets depends upon understanding the nature and mutuality of that relationship and because (2) choices have to be made about the protection and survivability of animals in the wild and in zoos and refuge areas. The relationship between humans and animals is shown to be an interrelationship in which ethics plays a large role.
Depending on the animal, our relationship is different. With some animals, human beings share something similar to a symbiotic relationship. We gain from them and they gain from us. For example, the domesticated animals such as cats, dogs and horses, receive protection from predators and weather and human beings receive companionship and work from them. Some other animals such as sheep and cattle are used for fur, milk, eggs, etc. and they receive food and protection. When discussing some other animals, such as deer, goat, chicken, cows, etc., we may share a predator-prey relationship. Human beings kill and consume such animals and are their predators. Human beings have very few predators, such as large carnivores (for example, tigers, lions, etc.) and with them we share prey-predator relationship.
With many other animals, we simply share our food web, they are part of it and help us in one way or the other. For example, detrivores (animals that consume dead or decaying matter) help clean our environment and we provide them with food.
Hope this helps.